Modified Atmosphere Packaging (MAP) is a practice of modifying the composition of the internal atmosphere of a package, generally in the field of food or drug storage, in order to improve shelf life. The modification process often tries to lower the amount of oxygen in the package, and sometimes replacing it with an inert gas. Reduction of the oxygen content for food and drug storage improves shelf life by slowing the growth of aerobic organisms. It can also slow the oxidation of certain reactions. Carbon dioxide (CO2) can be used to inhibit the growth of bacteria. The packaging typically can slow the movement of water vapor in or out of the package that may cause the products to degrade.